Rodgers is absolutely right to turn down the Liverpool job IMO, and any young manager looking to build their reputation is right to turn it down. He will know the expectations if he takes that job. He knows the Liverpool owners expect a top 4 finish pretty quickly. He knows he won't be able to compete with Man United, Emirates Marketing Project and Chelsea in the transfer market. He knows Spurs and Arsenal are already better and will keep improving. He knows Liverpool aren't made of money. Therefore he knows the chances of success relative to what Liverpool want are actually pretty slim. As a young manager forging his reputation, he would go to Liverpool, more than likely not get further than 5th or 6th unless he has a truly outstanding season, and everyone will look at him as not being good enough in the first place. But it will be gonads, and Rodgers knows that. He's very smart. It's not about not believing in himself enough, it's about being realistic about football and knowing that no matter how good he is, Liverpool probably will need an absolutely exceptional season to make 4th. Why would he want to put that pressure on himself? Why not stay at Swansea and build his repuation, and wait for the right job. I actually think for Rodgers, Spurs would be the right job. The expectations would be slightly lower and therefore we wouldn't damage his reputation as much as the near inevitable failure at Liverpool would.
Same reason Martinez turned down Villa. It was a little bit out of loyalty to Whelan, but also because he knows it isn't the right move. He knows they are slashing their wage bill and he wouldn't be able to take them much beyond mid-table. Therefore it's tough to achieve anything that would be perceived as success. If a club offers him the opportunity to prove himself, without unrealistic expectations, he would be off like a shot. Again, I think Spurs would suit Martinez in that way.
Liverpool really should end up with Capello or someone of that ilk. Somene that can satisfy the fans, and also has had enough success in the career that has already been built up to not need to succeed at Liverpool to progress. Capello would still probably only achieve 4th but he can walk away if he only gets 6th and say 'well I'm still a fudging good manager anyway, I've proved it at the top level before'. Rodgers couldn't, but it's about making the right career move. And he knows that. He's clever. He's waiting for us!